The BC327 is a popular PNP general-purpose transistor. This article will discuss the BC327 transistor’s features, specifications, equivalents, applications, and practical circuit implementations.

Catalog

BC327 Transistor Basic

The BC327 from onsemi is a PNP general-purpose transistor designed for reliable low-power switching and amplification. Housed in a compact TO-92 package, it supports up to –800 mA of collector current and 45 V collector-emitter voltage, making it suitable for driving loads, signal conditioning, and audio applications. Its wide gain ranges (BC327-16, BC327-25, BC327-40) provide flexibility for various design requirements while maintaining low noise and stable performance.

If you are interested in purchasing the BC327, feel free to contact us for pricing and availability.

BC327 Transistor CAD Models

BC327 Transistor Pinout Configuration

BC327 Transistor Equivalents

BC328

BC486

BC487

BC488

BC489

BC490

2N4403

BC327 Transistor Specifications

BC327 Electrical Characteristics

BC327 Transistor Application Circuit

LED Control Using Two BC327 Transistors

In the first circuit, two BC327 PNP transistors (Q1 and Q2) operate as complementary switches to control two LEDs. When the base of Q1 is pulled low through R5, the transistor turns ON, allowing current to flow from the positive supply through LED1 and R4 into the collector of Q1. This lights LED1 while also creating a voltage drop across R6. The voltage at point H drives the base of Q2: when Q1 is ON, the base of Q2 becomes more positive, keeping Q2 OFF, so LED2 remains unlit. When Q1 is OFF, the voltage at H rises toward the supply, reverse-biasing Q1 and lowering the voltage at Q2’s base via R6. This activates Q2, turning LED2 ON through R7. In simple terms, the BC327 transistors form an alternating LED control circuit—only one LED lights at a time depending on which transistor is conducting.

BC327 LED Driver Array

The second circuit uses two BC327 transistors to drive multiple LED strings from a 12V supply. Each BC327 functions as a high-side PNP switch that feeds several LEDs arranged vertically in series or groups. When the base of Q1 is pulled slightly lower than the emitter through its resistor network, Q1 turns ON and supplies current to LEDs LED1–LED5 and LED6–LED9. Similarly, Q2 provides current to the right-side LED banks (LED10–LED14) when its base is driven low through R3 and R4. Because the BC327 can handle up to 800mA, it is suitable for powering several low-current LEDs at once. The resistors at the top (R1–R4) set the current for each LED branch, ensuring stable brightness. This circuit demonstrates how BC327 transistors are excellent for distributing power to multiple light loads from a higher-voltage DC source.

Audio Power Booster Using BC327

In the third schematic, the BC327 serves as part of a complementary transistor pair to amplify an audio signal and drive a small speaker. The audio input is first filtered by capacitor C1 and amplified by NPN transistor Q1 (BC547). The resulting signal is then fed into Q2 (BC327 PNP), which works alongside Q3 (BC337 NPN) to form a push-pull amplifier stage. Diodes D1 and D2 provide thermal and bias stabilization, ensuring that Q2 and Q3 conduct smoothly without distortion at the zero-crossing point of the audio waveform. When the audio signal swings positive, Q3 drives the speaker; when it swings negative, Q2 conducts and supplies current to the speaker from the positive rail. The BC327’s ability to source significant current allows it to deliver stronger audio output to the 8-ohm speaker. This circuit highlights how the BC327 can be used in low-power audio amplifier output stages.

BC327 Transistor Applications

LED drivers

Switching circuits

Relay drivers

Audio amplifiers

Signal amplification

Motor controllers

Battery polarity protection

Level shifting circuits

Darlington pair configurations

Indicator/flasher circuits

Power distribution for small loads

Mechanical Dimensions

Advantages & Limitation

BC327 Advantages

High collector current capability (up to 800 mA)

Suitable for medium-power switching applications

Works well as a PNP high-side driver

Low saturation voltage for efficient switching

Available in compact TO-92 package

Good current gain (hFE 100+)

Easy to interface with microcontrollers using base resistors

Low cost and widely available equivalents

BC327 Limitations

Obsolete status

Limited power dissipation in TO-92 package (625 mW max)

Not suitable for high-voltage applications (45 V limit)

Higher currents may require heat considerations

Slower than power transistors for high-speed switching

Limited frequency capability for RF applications

Manufacturer

ON Semiconductor (onsemi) is a global manufacturer known for producing high-quality discrete semiconductors. The company maintains strict ISO-certified quality standards, offers AEC-qualified parts for automotive applications, and delivers reliable long-life product support. With a strong worldwide manufacturing footprint and expertise in power management, LED driving, motor control, and battery systems, onsemi ensures stable supply, high performance, and dependable reliability across a wide range of electronic applications.